Dynamics works better the more frames it has to animate and the more steps it has per frame. I can't really remember what the default steps for frame is (I'm rendering atm) but I always boost that. It's found in the dynamic panel where you set the number of frames and the collisions (polygon against polygon, polygon against vertex, etc).

I never check the box that says start the simulation with the figure at zero, but it always seems to anyway. LOL.

Laurie